Again I'll say that we aren't looking at that scope, we're looking at it from a standpoint of reproducingbeing a negative thing on a one generation standpoint and is that negative enough to cause the axe to fall (which it did more often than not, I'm guessing).
But that's the scope we should be looking at it from. There are way too many examples of behaviors that are detrimental to an individual but beneficial from the perspective of the species for me to list here, but suffice to say that cases of organisms doing apparently self-destructive things and passing on that tendency to offspring are well-documented, primarily because the societies/species with those organisms tend to have statistically better survival rates, meaning that their offspring are more likely to survive than if they were purely selfish.
It's technically not a disadvantage until they actually reproduce though, so perhaps that is the key to all this.
This is exactly what I was getting at. The competitive disadvantage doesn't become apparent or even significant until all the organisms less inclined to reproduce have already died out, at which point the tendency to reproduce permeates the gene pool.